Container for holding chemical solutions for processing films. Some tanks are for darkroom use only; others must be loaded in the dark, but can be used in daylight. (see Daylight Tanks)

The aluminum containers in the basket which hold the propane (a part of the balloon system)

Are containers for holding chemical solution for processing films.

thanks.

The First World War established the validity of the tank concept. Between the two world wars, many nations wanted tanks, but only a few had the industrial resources to design and build them. During and after World War I, Britain and France were the intellectual leaders in tank design, with other countries generally following and adopting their designs.

When the drilling, testing, completing and equipping of a well is finished the well is said to be completed "to the tanks".